1. Field of the Invention
The present invention relates to an image display technique.
2. Description of the Related Art
Many individual authentication media such as passport and identification (ID) card use facial images in order to allow individual authentication with visual check.
In the past, for example, a photographic paper having a facial image printed thereon was adhered to a booklet so as to issue a passport. Such a passport, however, may be tampered by replacing the photographic printing with another one.
For this reason, in recent years, information about the facial image tends to be digitalized, and the digitalized information is reproduced on the booklet. For example, thermal transfer recording method using a transfer ribbon is considered as the method for reproducing the image.
However, printers of thermal transfer recording method using sublimation dye or colored thermoplastic resin are widely available in recent years. In view of such circumstances, it is not necessarily difficult to remove the facial image from the passport and record another facial image thereon.
Jpn. Pat. Appln. KOKAI Publication No. 2000-141863 describes that a facial image is recorded by the above method, and the same facial image is further recorded thereon using fluorescent ink. Jpn. Pat. Appln. KOKAI Publication No. 2002-226740 describes that a facial image is recorded using ink containing colorless or light-colored fluorescent dye and colored pigments. Jpn. Pat. Appln. KOKAI Publication No. 2003-170685 describes that an ordinary facial image and a facial image formed with pearl pigments are arranged side by side.
When these techniques are applied to a passport, it is difficult to tamper with the passport. However, the facial image recorded using fluorescent material cannot be perceived unless a special light source such as an ultraviolet lamp is used. Although the facial image formed with pearl pigments can be perceived with unaided eyes, the particle sizes of pearl pigments are large, and therefore, it is difficult to form a high-resolution image using this.